HARRISBURG, Pa. (AP) — The Department of Conservation and Natural Resources secretary resigned at the governor’s request Thursday, but the reason was not immediately disclosed.

Gov. Tom Corbett issued a news release saying he had just “asked for and received” the resignation of Secretary Richard J. Allan Thursday morning. Corbett spokesman Kevin Harley declined to discuss the reasons for the change, calling it a personnel matter.

Allan, 60, has led the department since shortly after the first-term Republican governor took office in early 2011. He did not respond to messages at his home in Camp Hill, and a message was left at the department’s press office.

Allan has had a low profile in the Corbett administration, which he joined after a career in the scrap metal industry.

The department manages the state parks and forests, and has recently faced public opposition over potential drilling for natural gas in 100,000-acre Loyalsock State Forest. Some 500 people attended a public hearing on the issue last week, with opponents arguing the land was a public trust and voicing particular concern for drilling near Rock Run, a pristine stream.

Asked about the gas controversy, Harley said Allan’s departure “has nothing to do with any public policy. It was strictly a personnel issue.”

Environmental groups, however, said they hoped the change might translate into a shift in Corbett’s approach to drilling.

“I do think that the issue of gas development in the Loyalsock State Forest has become a defining issue for Richard Allan and Gov. Corbett when it comes to their conservation legacy,” said PennEnvironment’s executive director, David Masur.

Jeff Schmidt with the Pennsylvania chapter of the Sierra Club said the forced resignation came only days after he and others wrote the governor to alter his Loyalsock approach.

Allan graduated from Nanticoke Area High School and Wilkes University. He is also a member of the Penn State board of trustees.

The acting secretary, effective immediately, is Ellen Ferretti, who had been the deputy secretary for parks and forestry.